The long range purpose of this project is to establish the role of benzo(a)pyrene-4,5-oxide (BPO) hydratase in the metabolism of carcinogenic polycyclic aromatic hydrocarbons and in the initiation of tumorigenesis. Current work is in the areas of (1) characterization of red hepatic enzyme, (2) measurement of BPO hydratase activity in rodent target and human tissue, and (3) identification of modulators of BPO hydratase in in vitro and in vivo models of chemical carcinogenesis.